"The secret is a turntable bearing for a "Lazy Susan" that I bought at Lowe's for $7.50. It provides a stable low friction platform for the arms of the whirligig to connect to. Also, I used the drawing of the J/100 from your website to make scale models of the boats.
I took the video at our vacation home here in Cambridge, Maryland. Cambridge is on the Eastern Shore of the Chesapeake Bay across the Bay Bridge and about one hour south of Annapolis. The sailing here is great.
I am a member of the Eastern Shore Sailing Association. We do Wednesday night races and special distance races on Saturdays throughout Summer and Fall. I've single-handed my boat to Annapolis and to Solomon's Island from Cambridge. Both sails are about 40 miles. I've always felt safe sailing the J/100 even when the wind starts blowing hard and the seas kick up.
My J/100 is hull# 91. It was originally a dark gelcoat which I spruced up about three years ago with an Awlgrip finish -- it's a head turner! Here's a photo of us sailing in the waters off Cambridge area during a Wednesday night race." Best, Bob